Partial oxidation (PDX) of methane, ethane and propane were studied over mesoporous nanocrystalline Ni/Al2O3 catalysts with high surface area under different feed conditions. Various characterization techniques (XRD, SEM, BET, TPR and TPO) were employed for determining the chemicophysical properties of the prepared catalysts. The effects of active metal (Ni) content on the catalytic performance of the prepared catalysts were investigated and the results showed that 5 wt.% Ni/Al2O3 catalyst possessed the highest catalytic activity in the temperature range of 500-700 degrees C and atmospheric pressure. This catalyst was highly stable (in terms of activity and stability) for 48 h time on stream in methane partial oxidation. However, both the activity and selectivity declined gradually during 12 h time on stream for ethane and propane due to carbon formation. The TPO results revealed that the amount of carbon formed over the spent catalyst decreased by increasing in reaction temperature and O-2/CH4 molar ratio from 0.25 to 0.75. Furthermore, the use of higher hydrocarbons (C2H6, C3H8) in stoichiometric feed ratio increased the carbon deposition on the catalysts. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.